4 Aquarii

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4 Aquarii
Observation data
Epoch J2000      Equinox J2000
Constellation Aquarius
Right ascension 20h 51m 25.7483s
Declination -05° 37′ 35.878″
Apparent magnitude (V) 6.07
Spectral type F5V+
U−B color index 0.03
B−V color index 0.46
Variable type Variable star
Radial velocity (Rv) -24.6 km/s
Proper motion (μ) RA: 95.77 mas/yr
Dec.: 1.25 mas/yr
Parallax (π) 16.97 ± 1.26 mas
Distance 190 ± 10 ly
(59 ± 4 pc)
Absolute magnitude (MV) 6.48
Mass 1.7 M
Radius 1.4 R
Luminosity L
Temperature 6,000–7,500 K
Companion 4 Aquarii B
Period (P) 187 yr
Semi-major axis (a) 0.855"
Eccentricity (e) 0.47
Inclination (i) 68.3°
Longitude of the node (Ω) 173.9°
Periastron epoch (T) 1896.2
Other designations
BD-06° 5604, HD 198571, SAO 144877, WDS J2051.4-0538, HIP 102945, HR 7982.
Database references
Database references
Data sources:
Hipparcos Catalogue,
CCDM (2002),
Bright Star Catalogue (5th rev. ed.)

4 Aquarii or is a variable star with a spectral type of F5V. It is a white main-sequence star with strengthened H and K lines of Ca II and has neutral metal ionizations. 4 Aquarii is approximately 190 light-years from Earth with an absolute magnitude of 6.48.

4 Aquarii is a visual binary star.[1] 4 Aquarii B is .855" (degree seconds) from 4 Aquarii and orbits around the primary every 187 years. There are two optical companions.


  1. ^ Bartkevičius, A.; Gudas, A. (2002). "Kinematics of Hipparcos Visual Binaries. II. Stars with Ground-Based Orbital Solutions". Baltic Astronomy 11: 153–203. Bibcode:2002BaltA..11..153B.